Messages in this thread |  | | | Subject | RE: [regression]: soft lockup in dmesg after suspend/resume | | From | ykzhao <> | | Date | Wed, 06 Jan 2010 14:34:29 +0800 |
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On Wed, 2010-01-06 at 14:12 +0800, Zou, Nanhai wrote: > >>-----Original Message----- > >>From: Zhao, Yakui > >>Sent: 2010年1月4日 13:37 > >>To: mingo@elte.hu > >>Cc: linux-kernel@vger.kernel.org; Zou, Nanhai; Pallipadi, Venkatesh > >>Subject: [regression]: soft lockup in dmesg after suspend/resume > >> > >>Hi, > >> My box can work well before suspend/resume. But it will complain the > >>following warning message after suspend/resume. > >> >[1266874868.022103] Enabling non-boot CPUs ... > >>[1266874868.022198] BUG: soft lockup - CPU#0 stuck for 0s! [kthreadd:2] > >> > >> At the same time after I add the boot option of "printk.time=1", I > >>find that the log time is changed spontaneously from 76 to 1266874868. > >> > [ 76.475266] CPU3 is down > >>[ 76.475312] Extended CMOS year: 2000 > >>[1266874868.020631] x86 PAT enabled: cpu 0, old 0x7040600070406, new > >>0x7010600070106 > >>[1266874868.021779] Back to C! > >>[1266874868.022003] CPU0: Thermal LVT vector (0xfa) already installed > >>[1266874868.022060] Extended CMOS year: 2000 > >> > >> More detailed info can be found in the attached file of > >>dmesg_after_origin. > >> > >> After I look at the source code, I find that on this box the TSC runs > >>at constant rate with P/T states and does not stop in deep C-states. And > >>then the sched_clock_stable is set to 1. In such case the TSC time is > >>used directly in the function of sched_clock_cpu. > >> > >> Then I do another test on this box, in which the clock_stable flag is > >>saved/restored in course of suspend/resume(I add this by using per-cpu > >>structure). When entering the suspended state, the clock_stable will be > >>cleared. And when the system is resumed, the clock_stable will be set > >>again. But unfortunately the soft lockup still exists. The file of > >>dmesg_after_test2 is the dmesg log after I save/restore the clock_stable > >>flag in course of suspend/resume. > >> > >> How about clearing the sched_clock_stable flag even when TSC doesn't > >>stop in deep C-state? From my test it seems that the TSC value is > >>unknown after doing suspend/resume. > >> > >>Thanks. > >> Yakui. > > Hi Ingo, > How do you think about this bug? > This is introduced by the sched_clock_stable flag, > TSC is stable except when CPU is suspending, we see suspend/resume hang on those machines.
It is not suspend/resume hang. The main issue is that the kernel will complain the soft lockup warning message after suspend/resume. And when adding the boot option of "printk.time=1", we find that the dmesg log time will be changed spontaneously after suspend/resume.
thanks. Yakui
> Maybe we can ignore sched_clock_stable flag when CPU is suspending? > > Thanks > Zou Nan hai > >
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